Hydraulic knuckle



2 Sheets-Sheet 1 C. P. YOUNG HYDRAULIC vKNUCKLF Filed FC-b. 9, 1940 May20, 1941.

May 20, 1941.` c. P. YOUNG HYDRAULIC KNUCKLE Filed Feb. 9, 1940 2Sheets-Sheet 2 Patented May 20, 1941 UNlTEDST-TES PATENT OFFICE2,242,279 HYDRAULIC KNUCKLE.

Clarence P. Young, Bellflower, Calif. f sppiieauenrebmary 9, 1940,serial No. 318,046

1v claims.

' My invention, designated a' hydraulic knuckle, is for usemainly infishing jobs for tools or equipment lost in deep well drilling or forsimilar purposes. This may be considered as an improvement or furtherdevelopments of structures presented in the patent for a Hydraulic wallhook, P. G.`Gates et al., No,A 1,594,668, issuedAugust 3,- 1926 andWash-over hydraulic wallhook, No. 1,800,490, issued on April 14, 1931 tomyself.

AIn the construction `and the usage of a hinged or pivoted hydraulictype of joint, a number of problems arise such as securing the maximumbenet of the hydraulic pressure developed-by the slushing liquid pumpeddownwardly through the Well, hence by my present invention I utilizedisplacing pistons operating in a cylinder `in Vthe hydraulic block, thecylinders being transverse to the axis of said block and each being astraight cylinder and hence utilizing a straight piston moving thereforein a straight line direction. Such piston or pistons therefore have adirect outward thrust of their heads against a wall of the arm pivotedto the hydraulic block. A further feature of improvement is the mannerof supplying the liquid to the base of the cylinders by providing a ductor passage through the hydraulic block leading to one side of theuppermost cylinder and thence in succession to other cylinders where aplurality of these are utilized. The construction likewise applies for acirculation area around the pistons when retracted, hence providing anadequate space for a sufficient volume of liquid to provide for thedisplacement and outward movement of the pistons. A further detailfeature of my invention is in having the hydraulic cylinder or cylinderslocated below the hinge pintle of the joint instead of above as in thepatents above noted and thus avoid a double lever action in the movementof the pivoted or hinged arm. `Further, to develop an adequate thrustwith the maximum torque or leverage, such cylinders and their pistonsare presented in a vertical row as to the hydraulic block. The advantageof having the arm as a single lever resides in providing a -much longerleverage with the thrust pistons below the pintle and further in suchconstruction there is no upper part of the arm to be pressed sidewise.

Another detail feature of improvement is in the provision of a pluralityof stop pins or' lugs which have a pin and slot connection between thehydraulic block and the sides of the hinged arm operative to limit theoutward movement of such armY and further to provide additional strengthover that of the mainpintle or `hinge pin for pulling up or jarring on aiish caught by a suitable tool attached to the arm.

In the prior procedure of use and operating fishing tools attempts havebeen made `to 'obtain a wash-over of the fish by discharging slushingiiuid to loosen the'material in the well which becomes caught andembedded in the tool orwell equipment and prevents'its ready removal.With my invention I have developed a combination with the `ioint of thehydraulic construction for hinged joint as well as the downwarddischarge of slushing liquid under high pressure 'between the hydraulicblock connected to a string of drill pipe or -the like and the arm whichmay vhave attached thereto various fishing tools.

In this connection a feature of my invention includes a strong yetilexible tilting piping connectionbetween the lower end of the hydraulicblock and a sealing member mounted in Va cylindrical portion of the armand through which flexible member the flushing liquid-may be forceddownwardly under the desired high' pressure. In view of the -fact Vthatthis ilexibletilting tubular connection must provide for an angularmovement, my invention contemplates a flexibly mounted contact with ahydraulic connection to the passage and cylinders in the hydraulic blocknso that when the armV is displaced outwardly and the pumping oftheliquid is maintained, there will be a suiciently large volume ofslushing fluid discharged downwardly to start the upward circulation ofthe-dead fluid inthe lower partof the well, this also-provides fordischarge and circulation of oil wheresuch is needed for lubricatingpurposes.

Adetail feature of my invention in regard Yto the flexible tiltingconduit connection includes preferably providing a strong tube with aball and socket connection tothe lower end ofthe hydraulic block andproviding a flexible rubber seal inv a pipe forming part of the hinged`arm. This rubber seal is somewhat in the form of a cone shaped ortaperedannular gasket with the apex pointed downwardly and the tubeextending through the center. Therefore as the hydraulic fluid is forcedthrough the universal joint, the

tubing and `to a location below the seal, the bottom pressure buildingup closes and presses this annular gasket in close contact with the pipethereby preventing an upward fiow through the rubber seal. This coneshaped construction also permits an angular motion of the tube inrelation to the hydraulic` knuckle and to the hinged, arm, ,thislatterbeing due tothe ball and socket axis of movement being spacedconsiderably below`the main pintle of the hinge.

Another detail improvement is the construction and use of a hydraulicbean which is a metal block having an orifice therethrough positionedabove the ball and socket joint and below the lowermost cylinder. Theresistance of the bean to hydraulic ow thus causes the building up of asufficient hydraulic pressure in the cylinders to operate the pistons.

My invention is illustrated in connection with the accompanyingdrawings, in which:

Fig. 1 is a vertical section as if taken o-n the line of Fig. 3 or 5 inthe direction of the arrows illustrating, however, the pistons and thecylinder bushings in elevation and vertical section. This shows theknuckle in the retracted position with the arm in alignment forinserting in a well hole.

Fig. 2 is a section similar to Fig. 1 'with the arm in the extendedposition, the pistons being thrust outwardly and illustrating thepressure tube connection canted in a reverse direction to that of Fig.1.

Fig. 3 is a transverse section on the line 3-3 of Fig. 1 in thedirection of the arrows.

Fig. 4 is a side elevation taken in the direction of the arrow 4 of Fig.3 or 5.

Fig. 5 is a transverse section on the line 5-5 of Fig. 4 in thedirection of the arrows.

Fig. 6 is a side elevation similar to Fig. 4 on a reduced scaleillustrating the knuckle joint used with a wall hook in a well shingjob.

The hydraulic knuckle is composed of one of the main elements, thehydraulic block designated this being a substantially heavy metalstructure shown as provided with an internally screw threaded box I2 atthe top for connection to a string of drill pipe or the equivalent bywhich the tool is lowered into the well and the slushing fluid forceddownwardly by the pumps at thetop of the well. A duct I3 leadsdownwardly to conduct the slushing liquid and such duct enters an uppercylinder I4 on its upper side. Such cylinder is transverse to the axisof the hydraulic block and preferably has a slightly recessed inner endindicated at I5 to provide a relatively large capacity for the liquid.Below the upper cylinder there is illustrated a middle cylinder |6 and alower cylinder I1, these being connected by passageways |8 and I9respectively. All of the cylinders preferably have the same diameter anddepth and are preferably in vertical alignment. At the bottom of theblock there is a large recess for a universal joint and a uid passage 2|leading from the bottom cylinder to such recess.

The exterior of the hydraulic block is characterized by a bevel at theItop below the box structure, a circular section 26 therebelow, theopposite at sides 21 tov accommodate the portions of the arm hereunderdescribed. This leaves the partial circle 28 of the front section. Atthe back the hydraulic block has a flat side 29 and bevel corners 30from the sides 21 to the back 29. The shape of course may be departedfrom where desired. The back 29 thus forms part of a cord of thetransverse circle defining the upper portion of the hydraulic block. Atthe upper ends of the sides 21 there is the part circular socket 3|terminating at the shoulder 32 above the back 29. The hydraulic blockhas a hinge or pintle perforation 33 extending diametricallytherethrough from the sides 21 and immediately below the part circularsockets 3|. There are also stop pins 34 of which three are shown on eachside threaded into recesses 35 leading from the sides 21. These arepreferably all located on a radius line from. the pintle opening 33.These pins are illustrated as having a recessed wrench head.

Each of the cylinders has a bushing and piston assembly 40 havingthreaded bushings 4| threaded into a slight taper formed on the outerportions of the cylinders and extending inwardly from the back 29. Eachbushing has a slight shouldered recess 42. The pistons 43 are all of asimilar type having a piston head 44 slightly domed on its outsidesurface and of sufficient diameter to fit in the shouldered recess 42and seat against the bottom of such recess. Each piston has a chamberedinner end 45 forming a space to receive the hydraulic uid. This alsoreduces the weight of the pistons. The pistons when retracted areadapted to have the outside of the heads either flush with or slightlyinside of the surface of the back 29. It is to be noted that a duct I3for the flushing uid is on the front side of the pintle perforation 33,thus entering at the inner heads of .the cylinders.

It will be noted also that even when the pistons are in their innermostposition that there is suflcient space for the flow of liquid throughthe connecting passageways or ports I8 and I 9 and also as the pistonsare of less diameter than the cylinders, there is quite an ample annularspace around the pistons. These are guided solely in their extending andretracting movement by the bushings.

The arm assembly designated by the numeral 50 has opposite side members5| and a back poi'- tion 52. These are internally shaped with flatsurfaces, sides having a working t over the sides 21 of the hydraulicblock and also having an internal surface 53 which is flat and conformsto the back 29. There are also internal corner surfaces 54 correspondingto the surfaces 3|] of the hydraulic block. The upper ends of the sideshave ears 55 through which extends the main pintle 56 of the hinge, thisextending through the perforation 33 of the block. There is also asloping shoulder 51 at the upper end of the back which in the retractedposition of the arm is spaced from the shoulder 32. The back and sidesof the arm have a partly circular surface 58 which when the arm is inthe retracted position form with the surface 28 of the hydraulic block atrue circle in cross section. The sockets 3| as above noted areconcentric with the pintle 56 as is also the upper end of the ears 55 ofthe arm. There is a close flt between the ears and the socket.Therefore, on a down thrust part of this is transmitted directly betweenthe ears 55 to the socket 3|. This would take place when the arm is inthe retracted position as shown in full lines in Figs. 1 and 4. Byproviding the desired fit some of the thrust is removed from the pintle56 and from the pins 34. In any upward pull as in a jarring action thisis taken care of by the pintles and the pins in their respective slots.

The lower portion of the arm may be of different designs depending onthe purpose for which it is intended. In the illustration however thereis a tapered portion 65 connecting from the sides 5| and the back 52 toan integral tubular section 66, which is illustrated as externallythreaded at 61 at its lower portion for attachment of various tools. Ahydraulic seal assembly 15 utilizes an internal shoulder 16 in the tube66. Against this shoulder there is seated a fiat metal ring 11. Thisring forms a base or support for the rubber expansible packing ring orgasket 18, this being illustrated as provided with an annular baseportion 'I9 and a conical section 80 having a cylindrical opening 8|therethrough. The rubber gasket is held in place by an internallytapered gland 82 which is externally threaded and threads into internalthreads within the lower end of the tubular section 66, the inner end ofthe gland fitting against a shoulder portion 'I8 of the gasket. Throughperforation 8| is tted the fluid pressure tilting pipe 85. There is asuflicient sized opening in the ring 11 to accommodate any possiblemovement laterally of such pipe when the knuckle is shifted from theretracted to the yextended position.

The initial hydraulic pressure is built up in the upper part of thehydraulic block by utilizing a hydraulic bean designated by the assembly90. This is a metal block 9| screw threaded into the recess 2U andhaving a small orifice 92 communicating with the passage 2I anddeveloping a resistance to the flow of the slushing liquid. This bean isillustrated as having a recess 93 on its discharge side and also asforming the upper bearing for a universal joint assembly 95. 4This jointhas a sleeve 96 threaded into the recess 29. Internally the sleeve has atapered shoulder 9'I with a thrust bearing 9B engaged therewith. Theupper end of the tilting tube 85 has a tubular ball 99 connected theretoseated against the bearing surfaces on the lower part of the bean andthe bearing rings 98. To prevent leakage there is packing |09surrounding the ball and between the two bearin-g surfaces. The pipe 85while it 'is illustrated as rigid is part of a flexible pipe connectionas such terminology is used in the art. The ball and socket joint 99operating in the bearing and the hydraulic seal assembly 'i5 form withthe pipe 85 Moreover the gasket I8 being made of rubber is flexible andthus allows the pipe 85 in its tilting motion to have the flexiblehydraulic connection form the lower part of the hydraulic block to thetubular portion of the arm below the hydraulilc seal l5.

The side Walls 5I of the arm 59 are provided with arcuate slotsillustrated as three in number and designated IIB, III, and II2, eachbeing of increasing length and formed concentric with the pintle 56. Thestop pins 34 fit in these slots, the forward end H3 of these slotsdefining the limit of motion of the arm from its retracted to itsextended position.

The Amanner of operation and functioning of my invention is,substantially as follows: The hydraulic. joint may be connected at thelower end of a string of drill pipe as indicated in Fig. 6 and have asuitable tool attached to the lower end of the arm, this being indicatedas a wall hook to engage the upper end of a fish inclined in a well,however, the knuckle joint when lowered is in the retracted positionsho-wn in Fig. 4, then at the desired depth at which the tool is tooperate the slushing liquid is pumped downwardly through the drillstring from the surface of the well. `The rst reaction of the liquidwhich lls the passage I3, the cylinders I4, I6, and II under the pumpingpressure is to build up a high hydraulic pressure within the cylinders.At this stage of the operation the bean 90 having only a small orifice92 restricts the flow of liquid and hence causes the development of ahigh pressure within the bores. The pistons43 are thus forced outwardlyfrom the retracted posiexible connections.v

tion of Fig.- 1 to the extended position of Fig. 2. The heads of thepistons as above noted bear against the inner surface 53 of the backwall 52 of the arm and tilt the arm on its pintle 56 outwardly to theextended position. This extended position is limited by the studs 34secured to opposite sides of the knuckle block I I engaging theforwardends II3 of the respective slots III), I II and I I2 formed inthe sides of the arm. By having a plurality of pins the stresses due tothe outward thrust action is distributed.

Of course after the arm has been extended laterally and during themaintenance of the pumping of the slushing liquid, this is dischargeddownwardly through the o-rice 92 of the bean 99, thence through the pipeby the universal ball and socket joint 95 and the hydraulic sealconnection 15. This flow however does not interfere with the operationof a wall `hoo-k or other tool in catching afish inclined to one side ofthe axis of a Well hole and in centering such fish into axial `alignmentwith the well. When the fish has been properly caught by the wall hook,the l pumps may either be temporarily stopped or the hydraulic pressuredecreased so that the fish can be worked into axial alignment and thearm 59 retracted to its aligned' position. Some of these types of wallhooks are provided with slips or other devices to grip the flsh whenlproperly centered and when such is the case or the fish is aligned andheld in any suitable manner, then the pump pressure on vthe vslushingfluid may be increased, thence due to the fact that the fish being heldin position restrains the arm 59 from being thrust laterally,va1l of theflow of the slushing liquid is forced downwardly through the bean 95,the pipe 85 and dischargedl below the seal formed by the gasket 18. Itwill be noted that this gasket being formed of rubber may flex throughquite an angle from one side to the other as indicated by the changefro-m Figs. 1 to 2. The pressure being built up below this gasket onaccount of the .gasket being co-ned develops a squeezing pressure on therubber against the pipe 85 thus preventing upward leakage of theslushing liquid. The swinging movement of the arm 59 of course developsa slight up and down movement 'ci' the lower end of the pipe 85 relativeto the gasket as the distance between' the center of the ball and socketjoint 95 to the rubber seal is shortest when these are in verticalalignment and longest when the arm is extended as in Fig. 2. The rubberhowever yields to this motion or else allows a slight slip of the pipein the rubber.

In loosening and gripping a fish caught in a well and also on the upwardpull exerted to remove such fish, the sto-p pins 34 have an additionalfunction of taking part of the lifting stress which would otherwise comesolely o-n the pintle pin 56 as these pins have a close flt as to theupper edge of the slots within which they operate and thereforematerially add to the strength of the tool in removing a flsh from thewell. As the slushing liquid may be flushed downwardly around the fishor if the fish is caught in the proper type of tool through the fish,such liquid is operative to aid loosening the caught fish from the wellhole.

In :constructing the knuckle joint care should be takenthat there are noopenings leading into the arm and particularly the circular portion 6Bthereof by which dislodged large stones or the like may enter and thuspossibly break the pipeV 85 or damage the ball and socket joint or theseal y-'I5. Therefore the tapered portion Y65 of the arm 5i) forms afull circle as does also the portion immediately thereabove whichincludes the lower part of the back 52 and the sides 5l completing thecircle. 'I'he knuckle block on the front side is also 4continueddownwardly to align with the bottom, this being the portion designatedas having the surface 28. Thus when the arm is in the retracted positionof Figs. 1 and 4, there is only a small clearance space of insufcientsize to allow entry of any foreign material which might cause anyserious damage. It will be understood of course that the liquid such asoil, slushing liquid or water in the well hole enters this clearancespace as the tool is lowered and hence develops a hydraulic pressureequivalent to the hydraulic head in the well at any depth at which thetool is operated. While in the speciiication it has been mentioned thatthe usual hydraulic fluid for hinging the joint and for iiushingpurposes is the ordinary slushing liquid known as slushing mud, it isapparent that where circumstances warrant, oil may be pumped downwardlyand discharged below the seal for the purpose of forming a lubricant.

Various changes may be made in the details of the construction withoutdeparting from the spirit orl scope of the invention as dened by theappended claims.

I claim:

l. A hydraulic knuckle including in combination a knuckle block, an armhinged thereto, the knuckle block having a passage for iiow of liquid,the arm having a seal remote from the axis of the hinge and a tiltingflexible piping connection from the said block spaced from the hinge ofthe arm to and through the said seal to transmit hydraulic pressure fromabove the block to below the said seal.

2. A hydraulic knuckle including in combination a knuckle block, an armhinged thereto, the knuckle block having a passage for flow of liquid,the arm having a seal remote from the axis of the hinge and a tiltingilexible piping connection from the said block spaced from the hinge ofthe arm to and through the said seal to transmit hydraulic pressure fromabove the block to below the said seal, a hydraulic means in the blockand operative between the block and the arm to force the arm laterally.

3. A hydraulic knuckle including in combination a knuckle block, an armhinged thereto, the knuckle block having a passage for flow of liquid,

l the arm having a seal remote from the axis of the hinge and a tiltingflexible piping connection from the said block spacedv from the hinge ofthe arm to and through the said seal to transmit hydraulic pressure fromabove the block to below the said sea-l, the said block having one ormore hydraulic cylinders transverse to its axis and each having a pistonslidable therein, the piston or pistons having means to engage the saidarm and a connection from each cylinder or cylinders to the liquidpassage in the said block.

4. A hydraulic knuckle including in combination a knuckle block having alongitudinal liquid passage with one or more straight cylindersconnected thereto, each cylinder having a piston operative therein, anarm hinged to the block, the pistons being positioned to react againstthe arm to thrust such arm laterally on development of a hydraulicpressure through the said passage to the cylinder or cylinders, the armhaving a hydraulic seal remote from the end' of the block, a tiltingilexible pipe connection fromithe lower part of the block to and throughthe said seal,

and a liquid ow means connecting 'said pipe to the said passage of theblock.

5. A hydraulic knuckle having a knuckle block, an arm hinged thereto bya pintle, the block and the arm extending below the pintle, a hydraulicmeans including a liquid passage in the block for displacing the armlaterally, said displacing means beingbelow the pintle, the arm having atubular portion with a hydraulic seal and atilting flexible pipeconnection from the lower part of the block to and through said seal anda. liquid ow connection in the block from the said liquid passage to thesaid pipe.

6. A hydraulic knuckle having a knuckle block with a liquid passagetherethrough, an arm hinged to the block by a pintle adjacent the upperend of the arm, the block and the arm extending below the said pintle,one or more cylinders in the block connected to the liquid passage andeach having a piston therein reacting against the arm to thrust the armlaterally, said cylinders being straight and the said* pistons beingstraight to develop a straight line motion, the portion of the arm belowthe block having a tubular section with a hydraulic seal fitted thereintorestrain the leakage of liquid under pressure upwardly through saidseal and a pipe having a jointed connection with the lower portion ofthe block, there being a liquid connection in the block from the passageto said jointed connection and the pipe having a closed fit with theVsaid seal to transmit liquid under pressure from the block to andIbelow the said seal.

7. In a device as described, the combination of a knuckle block and anarm hinged thereto, the knuckle block having a passage for liquid, thearm having a tubular section with a hydraulic seal including a flexiblegasket, a pipe having a jointed connection with the block, there being aliquid connection from the passage to said jointed connection, the saidpipe having a tight t with the said gasket whereby liquid under pressureis transmitted through the pipe to and below the said seal, the saidgasket being adapted to form a tight closure on the pipe due tohydraulic pressure below the gasket.

8. A hydraulic knuckle including in combination a knuckle block havingtwo flat sides, an arm also having two sides with iiat inner surfacescomplementary to the flat sides of the block, a hinge pintle through thesides of the arm and the knuckle block, a passage for liquid through theknuckle block, a hydraulic means interacting between the block and thearm to extend the arm laterally, the arm having a tubular downwardextension, there being a slight clearance between a portion of saidtubular extension and the lower portion of the knuckle blockinsufficient in size for entry of obstructing material, a seal in thelower part of the tubular extension and a flexible hydraulic connectionbetween the block to and through the said seal.

9. A hydraulic knuckle including in combination a knuckle block having alongitudinal liquid passage with one or more straight cylindersconnected thereto, each cylinder having a piston operative therein, anarm hinged to the block above the cylinders, the pistons Ibeingpositioned to react against the arm below the hinge to thrust such armlaterally on development of a hydraulic pressure through the saidpassage to the cylinder or cylinders.

10- A hydraulic knuckle including in combination a knuckle block havinga longitudinal liquid passage with one or more straight cylindersconnected thereto, each cylinder having a piston operative therein, anarm hinged to the block above the cylinders, the pistons beingpositioned to react against the arm below the hinge to thrust such armlaterally on development of a hydraulic pressure through the saidpassage to the cylinder or cylinders, one or more stop pins having aWorking t connection between the arm and the block to limit the outwardmovement of the arm.

11. A hydraulic knuckle having a knuckle block, an arm hinged thereto bya pintle, the block and the arm extending below the pintle, a hydraulicmeans including a liquid passage in the block for displacing the armlaterally, said displacing means being below the pintle to react betweenthe portions of the block and arm below the pintle.

12. A hydraulic knuckle having a knuckle block with a liquid passagetherethrough, an arm hinged to the block by a pintle adjacent the upperend of the arm, the block and the arin extending below the said pintle,one or more cylinders in the block connected to the liquid passage belowthe pintle, and each having a piston therein reacting against the armbelow the pintle to thrust the arm laterally, said cylinders beingstraight and the said pistons being straight to develop a straight linemotion.

13. In .a device as described, the combination of an having a tubularsection, a liquid seal assembly mounted therein and including a exibleresilient gasket having a conical shaped portion facing downwardly andsaid gasket having a central aperture from top to bottom, means toconiine the peripheral portion of the gasket to prevent leakage, a pipeextending through the tubular portion of the arm and throughthe centralaperture of the gasket, means forming a hydraulic connection to theopposite end of the pipe adapted to develop an angular movement of thepipe in reference to the hydraulic seal, the conical portion of thegasket being adapted to move laterally with the pipe and the liquiddischarged by the pipe below the seal being adapted to develop hydraulicpressure on the gasket to form a seal against the pipe at the saidaperture.

14. A knuckle `ioint comprising in combination a knuckle block, an armhinged thereto by a pintle adjacent the upper end of the arm, the saidarm in the opposite sides having one or more pairs of slotsl below thepintle, the knuckle block having one or more pairs of pins attachedthereto below the pintle and fitting in said slots, a surface of theslots interacting with the said pins whereby when a sh or the like isengaged by the arm and an upward lift produced, the pulling stressesreact on all of the pins and the pintle.

15. A hydraulic knuckle comprising in combination a knuckle block havinga longitudinal liquid passage, a cylinder intersecting such passage, abushing at the open end of thel cylinder, a piston slidable and guidedin the bushing, a head on the piston seating on the bushing, the innerportion of the piston extending through the bushing where the head isseated on the bushing, there being a space between the inner end of thepiston and the cylinder, an arm having a hinged connection to theknuckle block by a hinge pintle located above the cylinder whereby onproducing a pressure of liquid in the cylinder the said piston forcesthe arm outwardly in a pivoted manner.

16. A hydraulic knuckle having a knuckle block, an arm pivoted thereto,a passage in the block and hydraulic actuated means to displace the armlaterally ycombined with a portion of the block extending below thepintle, the arm below the pintle having a tubular portion with ahydraulic seal and a liquid tight connection from the said passage inthe lower portion of the blo-ck to and through the said seal fortransference of liquid under pressure through the block to and beyondthe seal.

17. A hydraulic knuckle having a knuckle block, an arm hinged thereto bya pintle at the upper portion of the arm, the block and the armextending below the pintle, a hydraulic means including a liquid passagein the block with means reacting between the portion of the block andthe arm below the pintle to displace the arm laterally, the arm having atubular portion below the pintle with a hydraulic seal, a liquid tightconnection between the said liquid passage in the block to and below thesaid seal for transfer of liquid under pressure from the block to thearm below the seal.

CLARENCE P. YOUNG.

